This invention relates to a maleimide copolymer and a process for preparing the same.
There are known a variety of peroxy group-containing copolymers in the art. For example, there are known a copolymer of t-butyl peroxy methacrylate and methyl methacrylate in British Patent No. 1041088; a copolymer of t-butyl peroxyallyl carbonate with vinyl chloride in Japanese Patent Publication No.42083/1982; and a peroxycarbonate group-containing copolymer in Japanese Laid-open Patent Application No. 91209/1986.
However, in none of the above mentioned Publications, mention is made of a copolymer of a maleimide compound, an unsaturated peroxyester residue and a vinyl monomer.
On the other hand, it has been known to copolymerize the maleimide compound with various vinyl monomers to improve its thermal properties. For example, there are shown a copolymer of methyl methacrylate with an aryl maleimide in Japanese Patent Publication No. 9753/1968 and a copolymer of vinyl chloride and a maleimide compound in Japanese Patent Publication No. 12433/1969, both of these copolymers exhibiting high thermal resistance.
However, these copolymers has a disadvantage in that moldability and impact resistance are markedly lowered with increase in the ratio of the maleimide compound such that it is difficult to produce a copolymer having balanced properties.
On the other hand, as the process for preparing a graft copolymer of a vinyl monomer, there is proposed in Japanese Patent Publication No. 45647/1986 a process for preparing a graft copolymer comprising polymerizing a vinyl monomer in the presence of a peroxy group-containing copolymer by cleavage of the peroxy group.
However, there are not known in the art a graft copolymer of the maleimide compound and a process for preparing the graft copolymer.